The In Memoriam Prof. Peter Hafner Festival was first organised under this name in 2009, as a successor of sorts to the "Alter-Fest" that first appeared in 2005 at the Rdeča ostriga Club. In the beginning, Alter-Fest took place for only one evening and its line-up more or less consisted of punk bands. In the years to come, the festival widened its musical scope, forming a more varied and well-recognised programme. This development was partly due to the guidance of and help from Peter Hafner, a local music enthusiast, DJ, cultural activist, and mathematics professor, who unfortunately passed away in 2009. Thus, Alter-Fest got a new name.
After its initial punk orientation featuring bands such as Center za dehumanizacijo (CZD), the festival has gone for a more varied selection of musical orientations, from electronics to hip hop, bringing to stage some of the best alternative Slovenian acts and also a number of popular bands from abroad.
Of the local acts, one can mention Dubzilla, Moveknowledgement, Demolition Group, Koala Voice, We Can't Sleep at Night, Coma Stereo, Uršula Ramoveš in Fantje z Jazbecove grape, New Wave Syria, Bakalina, N'Toko, Marko Brecelj, and Ewok. Of the more memorable foreign acts, there are Rambo Amadeus, Damir Avdić, Punčke, Repetitor, Bad Copy, Erotic Biljan & His Heretics, and Vlasta Popić.